Fix Import variable binding for esprima 2

[adamjmcgrath]

eg import {foo as bar} from "baz";

The imported field refers to the name of the export imported from the module. The local field refers to the binding imported into the local module scope. If it is a basic named import, such as in import {foo} from "mod", both imported and local are equivalent Identifier nodes; in this case an Identifier node representing foo. If it is an aliased import, such as in import {foo as bar} from "mod", the imported field is an Identifier node representing foo, and the local field is an Identifier node representing bar.

See: https://github.com/estree/estree/blob/master/es6.md#importspecifier

[Constellation]

lgtm

[Constellation]

Thank you :D